> I could see an ISP
>giving everyone a /64, but only delegating DNS authority to those /64s who
>register themselves as networks.
I don't understand why an ISP would be interested in
providing a broken service offering to its customers.
>I guess it depends on how DNS will pan out in IPv6.
Unless it is administratively easy to provide customer configurable
DNS by some automatism, such services are likely not to be
offered to mass markets.
Personally I would look at this as an engineering challenge:
make something that works with ease, rather than limiting
the service offering.
-hph